(i) Technical Field
The present invention relates to focal plane shutters and optical instrument.
(ii) Related Art
Japanese Unexamined Patent Application Publication No. 6-250261 disclose: a board including an opening; an arm supported by the board, and blades coupled to the arm and capable of opening and closing the opening; and a sensor detecting a state of the blades. The sensor is arranged at a position opposite to the arm across the opening. The blades are composed of plural blades.
To suitably detect the state of the blades by the sensor, the blades need its size to sufficiently cover the sensor. For that purpose, it is considered that a blade extending in a direction perpendicular to the movable direction of the blades is employed. However, the large blade extending in the direction perpendicular to the movable direction of the blades is employed, thereby increasing the size of the board holding the blade in the direction where the blade extends. Thus, the size of the focal plane shutter is also increased.